Evaluation and extension of the load and fuel flexibility limits of a stratified downdraft gasifier

Synthetic gas generated from the gasification of biomass feedstocks is one of the clean and sustainable energy sources. In this work, a fixed-bed downdraft gasifier was used to perform the gasification on a lab-scale of rice husk, sawdust, and coconut shell. The aim of this work is to find and compare the synthetic gas generation characteristics and prospects of sawdust and coconut shell with rice husk. A temperature range of 650–900 °C was used to conduct gasification of these three biomass feedstocks. The feed rate of rice husk, sawdust, and coconut shell was 3–5 kg/h, while the airflow rate was 2–3 m3/h. Experimental results show that the highest generated quantity of methane (vol.%) in synthetic gas was achieved by using coconut shell than sawdust and rice husk. It also shows that hydrogen production was higher in the gasification of coconut shell than sawdust and rice husk. In addition, emission generations in coconut shell gasification are lower than rice husk although emissions of rice husk gasification are even lower than fossil fuel. Rice husk, sawdust, and coconut shell are cost-effective biomass sources in Bangladesh. Therefore, the outcomes of this paper can be used to provide clean and economic energy sources for the near future.

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Development of a New Sensor Module for an Enhanced Fuel Flexible Operation of Biomass Boilers

Processes ◽

10.3390/pr9040661 ◽

2021 ◽

Vol 9 (4) ◽

pp. 661

Author(s):

Martin Meiller ◽

Jürgen Oischinger ◽

Robert Daschner ◽

Andreas Hornung

Keyword(s):

Particle Size ◽

Bulk Material ◽

Detection System ◽

Wood Chips ◽

Convective Drying ◽

Characteristic Functions ◽

Biomass Combustion ◽

Fuel Flexibility ◽

Sensor Module ◽

Over Time

The heterogeneity of biogenic fuels, and especially biogenic residues with regard to water and ash content, particle size and particle size distribution is challenging for biomass combustion, and limits fuel flexibility. Online fuel characterization as a part of process control could help to optimize combustion processes, increase fuel flexibility and reduce emissions. In this research article, a concept for a new sensor module is presented and first tests are displayed to show its feasibility. The concept is based on the principle of hot air convective drying. The idea is to pass warm air with 90 °C through a bulk of fuel like wood chips and measure different characteristics such as moisture, temperatures and pressure drop over the bulk material as a function over time. These functions are the basis to draw conclusions and estimate relevant fuel properties. To achieve this goal, a test rig with a volume of 0.038 m3 was set up in the laboratory and a series of tests was performed with different fuels (wood chips, saw dust, wood pellets, residues from forestry, corn cobs and biochar). Further tests were carried out with conditioned fuels with defined water and fines contents. The experiments show that characteristic functions arise over time. The central task for the future will be to assign these functions to specific fuel characteristics. Based on the data, the concept for a software for an automated, data-based fuel detection system was designed.

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Downdraft gasifier design calculation for biomass gasification using exhaust gas as a gasification agent

Materials Today Proceedings ◽

10.1016/j.matpr.2021.03.520 ◽

2021 ◽

Author(s):

Sherif Elshokary ◽

Sherif Farag ◽

OSayed Sayed Mohamed Abu-Elyazeed ◽

Bitu Hurisso ◽

Mostafa Ismai

Keyword(s):

Biomass Gasification ◽

Design Calculation ◽

Exhaust Gas ◽

Downdraft Gasifier

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Simulation of a Downdraft Gasifier for Production of Syngas from Different Biomass Feedstocks

ChemEngineering ◽

10.3390/chemengineering5020020 ◽

2021 ◽

Vol 5 (2) ◽

pp. 20

Author(s):

Mateus Paiva ◽

Admilson Vieira ◽

Helder T. Gomes ◽

Paulo Brito

Keyword(s):

Modeling And Simulation ◽

Pilot Scale ◽

Operating Conditions ◽

Fuel Gas ◽

Heating Value ◽

Downdraft Gasifier ◽

Process Operation ◽

Independent Parameters ◽

Gasification Temperature ◽

Main Operating

In the evaluation of gasification processes, estimating the composition of the fuel gas for different conditions is fundamental to identify the best operating conditions. In this way, modeling and simulation of gasification provide an analysis of the process performance, allowing for resource and time savings in pilot-scale process operation, as it predicts the behavior and analyzes the effects of different variables on the process. Thus, the focus of this work was the modeling and simulation of biomass gasification processes using the UniSim Design chemical process software, in order to satisfactorily reproduce the operation behavior of a downdraft gasifier. The study was performed for two residual biomasses (forest and agricultural) in order to predict the produced syngas composition. The reactors simulated gasification by minimizing the free energy of Gibbs. The main operating parameters considered were the equivalence ratio (ER), steam to biomass ratio (SBR), and gasification temperature (independent variables). In the simulations, a sensitivity analysis was carried out, where the effects of these parameters on the composition of syngas, flow of syngas, and heating value (dependent variables) were studied, in order to maximize these three variables in the process with the choice of the best parameters of operation. The model is able to predict the performance of the gasifier and it is qualified to analyze the behavior of the independent parameters in the gasification results. With a temperature between 850 and 950 °C, SBR up to 0.2, and ER between 0.3 and 0.5, the best operating conditions are obtained for maximizing the composition of the syngas in CO and H2.

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